State-of-the-art implantable cardiac stimulation devices are equipped with multi-pole LV leads. Examples include quad-pole LV leads having four electrodes arranged from the distal LV apex to the proximal AV groove. When employed to deliver biventricular pacing in conjunction with an RV lead, it is desirable to determine optimal AV/VV pacing delays. For example, AV/VV pacing delays may be optimized for use with CRT, which seeks to normalize asynchronous cardiac electrical activation and resultant asynchronous contractions associated with congestive heart failure (CHF) by delivering synchronized pacing stimulus to both ventricles. That is, the AV/VV delays are set so as to deliver RV and LV stimulation pulses at optimal times to improve the overall cardiac function within the patient. CRT may have the additional beneficial effect of reducing the susceptibility to life-threatening tachyarrhythmias.
Optimization of AV/VV pacing intervals for use with CRT may also help to increase the number of responders to CRT as well as the quality and degree of response among CRT patients. Present methods of CRT optimization include: echocardiographic assessment of transmitral flow (i.e., the Ritter method); maximization of an echo-based aortic Velocity Time Integral; minimization of echo-assessed LV dyssynchrony; and electrical optimization based on surface electrocardiograms (ECGs/EKGs) or intracardiac electrograms (IEGMs.) Optimization techniques based on IEGMs include various QuickOpt™ techniques developed by the assignee of rights to the present invention, such as those described in U.S. Pat. No. 7,248,925.
Echocardiographic methods directly assess LV function but can be time consuming, operator dependent, and can lead to inconclusive timing recommendations. Electrical-based optimization methods such as QuickOpt™ are generally more convenient to implement, operator independent, and can be automated, but typically do not take into account the resultant LV function or any underlying electromechanical abnormalities and can be intrinsically reliant on the right atrial (RA) activation for timing cycle definition.
Accordingly, it would be desirable to provide AV/VV optimization techniques that have the efficiency and convenience of electrical-based techniques such as QuickOpt™ but also account for electromechanical properties of the heart of the patient. It is to this end that the present invention is generally directed.